1. Field of the Invention
The invention relates generally to methods and devices for treating neurological diseases and disorders affecting swallowing. The invention provides for the patient and the trainer of the patient to control the timing of switching stimulation to control a swallow at the optimal time when the patient desires to swallow.
2. Description of the Related Art
A wide range of neurological diseases and disorders exist that are not well addressed by present medical technology. Among these, dysphagia is a disorder placing persons at risk of aspiration pneumonia, a life-threatening condition. Subjects at risk of aspiration pneumonia have a 17% survival rate over three years. Estimates are that over 3 million persons in the U.S. have dysphagia as a result of neurological diseases or disorders such as stroke, traumatic brain injury, brain tumors, Parkinson's disease, multiple sclerosis and other neurological diseases and over 300,000 persons develop a swallowing disorder as a result of a neurological disease or disorder in the United States each year. Over 50% of subjects with neurological diseases or disorders are at risk of aspiration pneumonia because of loss of central nervous system control of their swallowing resulting in either delayed or reduced elevation of the hyolaryngeal complex, which does not allow them to prevent food or liquid from entering the airway. Normally the hyoid and larynx are raised by about 20 mm during swallowing producing an inversion of the epiglottis and assisting with opening of the upper esophageal sphincter. Many therapeutic techniques aim to improve hyolaryngeal elevation and reduce aspiration risk in dysphagia.
Many other disorders need treatment, particularly as a result of stroke and other neurological diseases. In addressing these treatment needs, research has demonstrated that somatosensory stimulation can potentiate recovery of hand movement post stroke.
Others have shown that somatosensory stimulation applied to a paretic hand has transient beneficial effects on the paretic hand pinch force in patients with stroke. It has previously been shown that electrical, heat or a bolus in the hypopharynx can trigger swallowing while laryngeal sensory blocks will severely impair the initiation of volitional swallowing in normal adults. Pharyngeal stimulation can initiate laryngeal closure and elevation for swallowing in animals, while laryngeal stimulation will trigger a swallow. In humans, when sensory stimulation of the oropharynx is presented during a period separate from swallowing, it enhances cortical activity in the swallowing regions, but does not benefit subsequent swallowing in dysphagic subjects. Thus, further discoveries are needed in this area.
Broad methods and devices are presented for therapy of neuromuscular disorders such as dysphagia. By training subjects afflicted with dysphagia to coordinate their own swallowing with intramuscular stimulation, their central volitional control was found to also improve, without stimulation after training. Subjects could improve quickly in their ability to trigger stimulation at the same time as intended swallow. Results indicate that normal persons can easily and spontaneously coordinate the onset of a button press with the onset of muscle activation for the pharyngeal component of swallowing. Accordingly, subjects with dysphagia can learn to coordinate a muscular movement such as a button press with swallowing onset. In other embodiments, other muscle movements similarly are quickly learned in a similar manner.
Therefore, there is need for device to permit the patient to coordinate muscular movement with a button press to permit volitional swallowing.